Which of the following is a method of refining (purification) of metals?
A. Poling
B. All of the above
C. Liquation
D. Zone refining
Answer: Option B
Solution (By JKSSB Mock Tests)
Refining is the final step in metallurgy to obtain pure metal. Poling is used for copper to remove oxide impurities. Liquation separates low-melting metals (like tin) from high-melting impurities. Zone refining is used for producing ultra-pure semiconductors (like Si, Ge) based on the principle that impurities are more soluble in the molten state.
Explanation:
Fertilizer grade is expressed as N-P₂O₅-K₂O percentage by mass. So 15-15-15 means 15% N, 15% P₂O₅ (not elemental P), and 15% K₂O (not elemental K). To convert P₂O₅ to P, multiply by 0.44; K₂O to K by 0.83. This is a balanced compound fertilizer providing all three primary macronutrients.
Explanation:
Nickel (finely divided) catalyzes the addition of hydrogen to unsaturated vegetable oils to form solid vanaspati ghee. It provides surface for reaction. Platinum and palladium also work but are expensive. Iron is used in Haber process. V₂O₅ in Contact process.
Explanation:
In [Ni(CN)4]2-, Ni is in the +2 oxidation state (d8 configuration). CN- is a strong field ligand, causing the pairing of d-electrons. This leaves one empty d-orbital, leading to dsp2 hybridization. The geometry is square planar. Since all electrons are paired, the complex is diamagnetic.
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